This invention relates generally to a cooling tower and in particular to a counter-flow forced-draft type cooling tower.
Conventionally, cooling towers are divided into three types. These are the atmospheric, natural draft and forced draft types. These three types, in turn may be sub-classified into counter-flow or cross-flow type cooling towers.
In an atmospheric type cooling tower, high temperature water is pumped to the top of the cooling tower, where it then falls as a free body. During the free fall period heat is transferred from the higher temperature water to the lower temperature air, thereby decreasing the temperature of the water.
The atmospheric cooling tower has the simplest design of the three above-mentioned types, but its efficiency is quite low.
In a natural draft type cooling tower, the cooling tower is basically a chimney which causes the low temperature air to flow upwards. High temperature water is then sprayed from the the top of the cooling tower, and falls downwards. When the water and air come into contact, heat is transferred from the water to the air. Since the flowrate of air within the cooling tower is affected by the wind speed around the cooling tower, its efficiency fluctuates.
In forced-draft type cooling towers, low temperature air is drawn into the cooling tower mechanically. This increases the efficiency of heat exchange between the high-temperature water and the low temperature air over natural draft type cooling towers. However, a cross-flow forced-draft type cooling tower have a great disadvantage that it takes up more space than a counter-flow type cooling tower.
Although the counter-flow forced-draft type cooling tower is more efficient than other types of cooling towers, it is still possible to improve it. Therefore the object of the present invention is to provide a counter-flow forced-draft type cooling tower with a higher heat exchange rate than prior art.
As shown on FIG. 4, a conventional counter-flow forced-draft type cooling tower usually has a fan 201 disposed above the cooling tower 200'. This can be improved as shown on the following detailed description to increase its function.